U.S. safety regulators are adding the Dodge Durango to an investigation of ceiling fires in Jeep Grand Cherokees. The National Highway Traffic Safety Administration says the probe now covers more than 593,000 SUVs from the 2011 through 2013 model years.

The agency says an analysis of Chrysler data shows 52 possible fires and three injuries. Customers reported minor overheating or flames. Investigators are focusing on an electrical short. The Durango was added because it has the same ceiling and visors as the Grand Cherokee.

The agency began the investigation in August but so far, no recall has been ordered.